Hydrogenation of residuum

ABSTRACT

In the hydrodesulfurization of bitumen from certain natural tar sands, such as the Athabasca sands, acceptable hydroconversion levels can be obtained by the use of particulate contact solids operating in an upflow liquid phase ebullated bed system at a conversion rate such that a maximum heptane-insoluble number of 40 is not exceeded. The parameters of operation depend to some extent on the solids in the bitumen.

United States Patent [1 1 Layng 1 Jan. 21, 1975 41 HYDROGENATION'OF RESIDUUM [75] .lnventor: Edwin Tower Layng, Summit, NJ.

[73] Assignee: Hydrocarbon Research, Inc., New

York, NY.

221 Filed: Jan. 2, 1973 21 App1.No.:320,573

[52] US. Cl 208/108, 208/11, 208/48 R, 208/158, 208/216 511 Int. Cl..... Cl0g 9/16,C10g l3/02,C10g 23/02 [58] Field of Search 208/108, 107, 112, 10, 208/11, 48 R [56] References Cited UNITED STATES PATENTS 3,151,054 9/1964 Layng 208/11 3,412,010 11/1968 Alpert et al 208/112 3,681,231 8/1972 Alpert et a1 208/59 3,725,247 4/1973 Johnson et al 208/111 3,775,296 11/1973 Chervenak et a1 208/108 Primary Examiner-Paul M. Coughlan, Jr. Assistant Examiner-G. E. Schmitkons [57] ABSTRACT In the hydrodesulfurization of bitumen from certain natural tar sands, such as the Athabasca sands, acceptable hydroconversion levels can be obtained by the use of particulate contact solids operating in an upflow liquid phase ebullated bed system at a conversion rate such that a maximum heptane-insoluble number of 40 is not exceeded. The parameters of operation depend to some extent on the solids in the bitumen.

4 Claims, 1 Drawing Figure Mime UVEQf/MD LEI/EL 2 56 Z/Qu/O LEVEL HYDROGENATION OF RESIDUUM BACKGROUND OF THE INVENTION The ebullated bed system described by Johanson in US Reissue Pat., No. 25,770, has proved successful in hydrogenation of petroleum residuum, including hydrocracking and hydrodesulfurization of a wide variety of stocks. The advantages of high throughput, uniform temperature, low pressure drop and non-plugging characteristics have been of great benefit to residuum processes. Liquid phase conditions assure good catalyst contact with no substantial attrition, and with the inter nal recirculation the catalyst bed has an average age which can be easily changed, without stopping the operation, by the mere addition or withdrawal of catalyst.

In processing the bitumen from natural tar sands, such as Athabasca sands which contain a substantial amount of asphaltenes and inert solids including sand,

it was observed that during apparently satisfactory operations a tarry, sticky material was continuously formed over a period of a few days on stream at a conversion in excess of 50 percent of the material boiling over 975F. Lower conversion rates become economically unsatisfactory.

SUMMARY OF THE INVENTION The hydroconversion of a bitumen derived from natural tar sand having at least 50 weight percent boiling above 975F such as Athabasca tar sands and similar tar sands materials containing substantial amounts of asphaltenes and inerts can be accomplished on a continuous high level basis in an ebullated bed system by limiting conversion to not exceed the production of a product having a critical heptane insoluble number. This can be accomplished by variations in operating conditions such as lower temperatures, higher pressures and maintaining a limited solids addition and removal rate such that this heptane insoluble number is not reached.

DESCRIPTION OF THE DRAWING The FIGURE is a schematic view of an ebullated bed reactor.

PREFERRED FORM OF EMBODIMENT As more specifically shown in the drawing, an asphaltene and inert sand containing bitumen feed and hydrogen from line 12 are fed by line 14 upflow through a reactor generally designated 18. This reactor is typical of that shown in US. Reissue Pat., No. 25,770. The reactor has a liquid distributor and contact solids support so that the liquid and gas passing upwardly through the reactor 18 will tend to put the solids in random motion in the liquid.

The contact particle size range is usually a narrow size range usually between 3 and 325 mesh (U.S. Std.) or sand having a size of less than 10 microns for uniform expansion under controlled liquid and gas flow conditions. An upflow liquid velocity between 1 and 100 gallons per minute per square foot of reactor cross section will maintain the bed of solid particles ebullated without substantial carryover of the solids. The solids may be the residual tar sand themselves or a catalyst but I find that the bitumen heretofore treated having high levels of sandconcentration was most effectiveylf the bitumen was low in sand, recycle would concentrate the sand to be most effective as described in my US. Pat. No. 3,151,054. The liquid flow rate, the density of the solids and the lifting effect of the hydrogen are factors in the buoyancy of the solids.

By control of the solids particle size and density and liquid and gas velocities and taking into account the viscosity of the liquid under the operating conditions, the solids bed may be expanded to have a definite level or interface in the liquid as indicated at 22. The settled level of the solids would be considerably lower than level 22. Normally bed expansion should be at least 10% and seldom over of the static level.

In a reactor system of this type, a vapor space 23 is provided above the liquid level 56 from which a vapor overhead completely free of liquid, is removed at 24. The gaseous portion which is largely hydrogen, may be recovered by conventional means and after being reheated can be recycled to the feed line 14 to the reactor.

A heavy liquid, substantially free of solids, is separated from the effluent in the upper part of reactor 18 by trap tray 43 and drawn off at 44.

If a catalyst is used, it can be a typical hydrogenation catalyst from the group of cobalt, molybdenum, nickel and tungsten and mixtures thereof carried by a support from the group of silica, alumina and mixtures thereof.

Circulation of liquid from above the solids interface 22 to below the distributor deck 20 may be desirable to assure completeness of the reaction and to establish a sufficient upflow liquid velocity to assist in maintaining the solids in randon motion in the liquid. As described in the Johanson U.S. Reissue Pat., No. 25,770, recycle can be established by an external pump on heavy liquid line 44 with a connection back to feed line 14.

Operability of the ebullated bed system to assure contact and uniform (iso-thermal) temperature depends on the random motion of the relatively small solids in the liquid environment resulting from the buoyant effect of the upflowing liquid and gas. With a non-uniform distribution of liquid flow, upsets take place, usually resulting in coke deposits.

Different tar sand feedstocks are found to have more or less asphaltene coke pre-cursors which tend to aggravate the operability of the pumps and recycle piping due to the plating out of tarry deposits. While these can be washed off by lighter diluent materials, the unit may become completely coked up and require premature shut down.

I have found that I can anticipate such condition by the use of a test procedure which I designate as the heptane insoluble number (HIN). Such test, an adaptation of ASTM (American Society for Testing Materials) test D 1796 is as follows:

50 cc of reactor liquid are mixed with an equal volume of heptane, heated to F and centrifuged for 20 minutes. The material thrown out of solution, expressed as a percentage of the oil is designated the HIN (heptane insoluble number).

As described hereinafter, certain tests were made on the products from bitumen of the following type:

INSPECTION ON ATHABASCA TAR SANDS BITUMEN Gravity. APl 8.9 5.5 8.5

-Continued INSPECTION ON ATHABASCA TAR SANDS BlTUMEN While a preferred form of embodiment of the invention has been shown and described, I am aware that modifications may be made thereto within the scope and spirit of the disclosure herein and of the claims ap- 5 pended hereinafter. Sulfur, w1. 4.88 4.85 4.92 I claim: 333mg; g? 2;? l. A process for enhancing the operability of an ebul- Hydrogen, Wt. 10.51 10.15 10.73 lated bed system for the hydroconversion of a residuum ppm 3900 bitumen feedstock derived from natural tar sands and Metals, ppm 455 493 l havmg at least 50 weight percent of hydrocarbons bo1ling above 975F and composed substantially of asphal- A number of runs were made varying the factors of lanes, Where!" the feefistock and f 'P Pa "P- solids and catalyst, space velocity, hydrogen through-- wardly through a regctlon Zone g g partlculate put, temperature and pr contact matenal having a close size range in the range The following examples i h operating d il l of 3 to 325 mesh (U.S. Std.) under conditions to place EXAMPLES 1 11 111 1v v v1 Stock No. 3332 3241 L-329 L-330 L-324 L-33l Run 185-169 185-148 201-53 201-54 185-167 201-55 70 Ash in ,7

Reactor 32.1 3.9 18.9 48.8 30.0 Temperature 820F 820 820 820 820 820 Pressure,psig 750 750 750 750 750 750 Space Velocity v,/11r/v, 1.5 1.5 1.5 1.5 1.5 1.5 Gravity APl 9.6 3.2 7.l 6.4 5.l s Wt. 4.68 4.94 5.34 5.01 5.02 Ash. Wt. 0.62 4.02 0.47 1.83 3.04 Carbon. Wt. 83.5 80.6 11,. W1. 71 10.55 10.04 BS&W.W1.% 1.5 6.8 1% 3% 5.6 HlN 32 26 48 38 40 v Results Plugged Satis. Plugged Outline Coked Salis.

Restricted While specific examples are set forth above, I find the following parameters for hydroconversion of tar sand bitumen to be generally applicable:

Range Preferable Space Vel. V,/l1r/V,. 0.5 2.0 0.8 1.5 Pressure. psig 750 2000 I200 max. Temperature, "F 750 850 about 825 the contact particles in randon motion in the liquid, and hydroconversion conditions are maintained in the reaction zone in a temperature range between about 750 and 850F, and total pressures are in the range of 750-2,000 psig, and with a space velocity in the range of 0.5 to 2.0 V,/hr/V,, the improvement which comprises maintaining reaction conditions such that the liquid effluent from the reaction zone has a heptane insoluble number under 40.

2. A process as claimed in claim 1 wherein the feedstock is a bitumen recovered from Athabasca tar sands, and the heptene insoluble number is kept below 32.

3. A process as claimed in claim 1 wherein the conversion of materials boiling above 975F to materials boiling below 975F is above 50%.

4. A process as claimed in claim 1 wherein the bitumen contains in the order of less than 1% of ash and the operating pressure is in the order of 750 psi hydrogen partial pressure, the temperature is in the order of 820F, the space velocity is about l.5 V;lhr/V,. and the conversion of 975F plus material is over 60 percent. 

1. A PROCESS FOR ENHANCING THE OPERABILITY OF AN EBULLATED BED SYSTEM FOR THE HYDROCONVERSION OF A RESIDUUM BITUMEN FEEDSTOCK DERIVED FROM NATURAL TAR SANDS AND HAVING AT LEAST 50 WEIGHT PERCENT OF HYDROCARBONS BOILING ABOVE 975*F AND COMPOSED SUBSTANTIALLY OF ASPHALTENES, WHEREIN THE FEEDSTOCK AND HYDROGEN PASS UPWARDLY THROUGH A REACTION ZONE CONTAINING PARTICULATE CONTACT MATERIAL HAVING A CLOSE SIZE RANGE IN THE RANGE OF 3 TO 325 MESH (U.S. STD.) UNDER CONDITIONS TO PLACE THE CONTACT PARTICLES IN RANDON MOTION IN THE LIQUID, AND HYDROCONVERSION CONDITIONS ARE MAINTAINED IN THE REACTION ZONE IN A TEMPERATURE RANGE BETWEEN ABOUT 750* AND 850*F, AND TOTAL PRESSURES ARE IN THE RANGE OF 750-2,000 PSIG, AND WITH A SPACE VELOCITY IN THE RANGE OF 0.5 TO 2.0 VF/HR/VR, THE IMPROVEMENT WHICH COMPRISES MAINTAINING REACTION CONDITIONS SUCH THAT THE LIQUID EFFLUENT FROM THE REACTION ZONE HAS A HEPTANE INSOLUBLE NUMBER UNDER
 40. 2. A process as claimed in claim 1 wherein the feedstock is a bitumen recovered from Athabasca tar sands, and the heptene insoluble number is kept below
 32. 3. A process as claimed in claim 1 wherein the conversion of materials boiling above 975*F to materials boiling below 975*F is above 50%.
 4. A process as claimed in claim 1 wherein the bitumen contains in the order of less than 1% of ash and the operating pressure is in the order of 750 psi hydrogen partial pressure, the temperature is in the order of 820*F, the space velocity is about 1.5 Vf1hr/Vr and the conversion of 975*F plus material is over 60 percent. 